Temperature is one of physical quantities of the seven basic units set by the International System of Units and is also one of the most basic physical quantities of materials in the nature. Temperature measurement is of great importance for cognition of nature of materials in the nature. Magnetic nano temperature measurement method, a brand new temperature measurement method characterized in non-invasion, obtains temperature information mainly by measuring magnetization of magnetic nanoparticles and by inverse calculation based on certain model. Non-invasion property of magnetic nano temperature measurement method makes it have broad application prospects under special circumstances such as deeply in vivo and in other confined spaces.
Temperature measurement deeply in vivo and in other confined spaces remains a worldwide problem severely hindering development of related applications in the biomedical field such as tumor hyperthermia and drug transportation. Tumor hyperthermia technique, a tumor surgery known as the “Green Treatment” characterized in non-invasion or mini-invasion, treats a tumor mainly by differences of temperature tolerance between normal cells and tumor cells in vivo. Drug transportation technique releases a drug at a designated location and a predetermined amount by magnetic nanoparticles coated with drug laden polymer and by RF heating, where measuring and controlling temperature of the magnetic nanoparticles is critical to releasing the drug at a designated location and a predetermined amount. Unfortunately, at present, although temperature measurement technique under normal circumstances such as thermal resistances has already been very mature with properties of high precision and high real-time, temperature measurement technique under special circumstances such as deeply in vivo remains developing slowly. Challenges in temperature measurement in vivo mainly lie in the special circumstance in vivo and its safety requirements, which makes contact and non-contact temperature measurement methods in prior art inapplicable. Therefore, breakthrough in temperature measurement in vivo is bringing a technical revolution to related biomedical applications, and temperature measurement in vivo with high precision and high real-time remains a worldwide problem to be solved.
Development of related magnetic measurement technology brings twilight to solving the worldwide problem of precise and real-time temperature measurement in vivo. In recent years, development of magnetic resonance thermometry provides a reliable solution to temperature measurement in vivo. In 2008, Warren et al. realized high-precision temperature imaging by coherence of inner molecules in magnetic resonance, which is significant for research in tumor hyperthermia and drug transportation. Besides, in 2009, J. B. Weaver realized magnetic nano temperature measurement through experiments by amplitude ratio between the triple harmonic generation and the quintuple harmonic generation of AC magnetization of magnetic nanoparticles. In 2012, Liu Wenzhong realized precise temperature measurement using magnetic nanoparticles by DC magnetic susceptibility of magnetic nanoparticles and by derivation and experimental verification of theoretical models based on Langevin's function model, and finished theoretical model research on temperature measurement using magnetic nanoparticles by AC magnetic susceptibility of magnetic nanoparticles and by simulation afterwards. The researches pave the way for non-invasive temperature measurement in vivo, however, due to lack of proper theoretical model research and adequate experimental research, magnetic nano temperature measurement technique remains immature, in particular, real-time and precise temperature measurement technique lacks adequate theoretical and experimental researches. Therefore, realizing non-invasive, real-time and precise temperature measurement remains an urgent problem to be resolved in technical fields like biomedicine.